ACTG 401-This study looked at the effect of ritonavir and saquinavir, protease inhibitors used in the treatment of AIDS, on the elimination of methadone from the body. In addition, the study looked at whether there was too much narcotic affect or not enough narcotic effect when these drugs are used together in patients on methadone for narcotic addiction. The study found that the combination of ritonavir and saquinavir could be used safely with methadone without concern for too much or too little narcotic effect